The present invention relates generally to devices to provide a covering for the opening of a container and is particularly useful in the food processing industry where the container is carried on a conveyor, is filled with selected food items, and a cover is then applied to the container.
In such application, including other applications to which the present invention applies the material to be packaged is usually placed in a deep drawn tray, for example an aluminum fiber or plastic tray. The trays usually have a generally transversely extending peripherial flange around a portion of the tray to receive the cover material and in some instances the flange also supports the tray in the conveyor aperture.
In food processing industry applications cleanliness of the operation, ability to cleanse the operating equipment, and minimization of the risk of exposure of the container and product to contaminates are of considerable importance.
Various prior art means are known for providing a cover for containers and for sealing the containers.
One such arrangement is shown in U.S. Pat. No. 4,102,113 where individual covers are supplied to containers traveling on a conveyor line and are mechanically sealed. Other arrangements are shown in U.S. Pat. Nos. 3,268,393 and 2,595,849.
While the foregoing arrangements are satisfactory for applications where the cover is mechanically attached to the device, in other applications a flexible or other type covering is applied, for example, in a web form, and adhered to the containers as they move along the conveying line. Devices heretofor provided for application of web type covers to traveling containers have generally included a drum type seal arrangement but such devices have been limited in speed because of the contact time required to provide an adequate seal for the covering on the container.
No prior art device is known where a carriage travels with containers in a conveyor line to seal the conveyors and permit improved processing speed.